Nine type A influenza viruses were isolated from the feces of ringbill gulls collected on golf courses and football fields of Baltimore, Maryland during April and October, l978. One hemagglutinin subtype was Hav5 and all others could not be typed using conventional H-I tests. The associated neuraminidase was Nav6 as typed by elution-inhibition methods. Thus, during the past 18 months, gulls have yielded 5 different hemagglutinins (H2, Hav3, Hav5, Hav6, Hav7) and 4 different neuraminidases (Neg2, Nav1, Nav4, Nav4, Nav6). Nav6 was found in combination with 3 of the hemagglutinins (H2, Hav3, Hav5) suggesting a frequent occurrence of genetic reassortment among the gull influenza viruses. Antineuraminidase antibody, detected by elution-inhibition with types Nav4, Nav6 and N2 was present with prevalences of 7%-26% in mute swans, whistling swans and ringbill gulls but less so in Canada geese. Similarly, H-1 antibodies for H2, Hav3, Hav6 and H3 hemagglutinins were prevalent in all species except Canada geese. The ubiquity of antibody in swans for the antigen present in influenza viruses isolated from ringbill gulls indicates that the viruses may commonly infect swans but not necessarily Canada geese. The geese and mute swans share the Chesapeake Bay habitat with gulls. Attempts to isolate viruses postulated from the H-1 and E-1 antibody results from swans and geese are in progress.